Topic #536 on this forum has a number of posts on this issue. I have the same sound in mine, first noticed after about 3 days of driving. Everyone describes it the same way, as a ticking that sounds the way a loose lifter used to. One tech on this board says it is just a function of the valve noises not cancelling each other out, but I don't buy that. I believe this engine was meant to purr when new and for as long as possible after.

I alerted my dealer/tech and they said to drive it some more, that it may take some miles for all the seals to saturate/seal.

My Voyager had a very similar sound for years, and what it meant over time was that it burned more and more oil. Ticking tends to become tapping. Some may say MB designed this engine to alert Captain Hook, but I think that's a croc.